Our kidneys perform the important function of filtering waste products and excess water from the blood, producing urine. This filtering capability is measured by the glomerular filtration rate, or GFR. Understanding your GFR assesses the health and function of these organs.
Understanding Your eGFR
The estimated glomerular filtration rate, or eGFR, is a measure of kidney filtration efficiency. It is determined using a blood creatinine test, along with your age, body size, and gender. Creatinine is a waste product from muscle metabolism that healthy kidneys remove from the blood.
The eGFR calculation provides an estimate of kidney function, helping medical teams assess your kidney health. While largely reliable, the eGFR may be less accurate for individuals under 18, pregnant, or those with extreme body weight or muscle mass.
Interpreting Your eGFR Results
For adults, a normal eGFR number is above 90 mL/min/1.73 m2, indicating healthy kidney function. An eGFR of 123 mL/min/1.73 m2 falls within this normal range, suggesting your kidneys are functioning effectively. It is worth noting that eGFR naturally decreases with age, even in individuals without kidney disease.
A lower eGFR can indicate reduced kidney function. If eGFR is below 60 mL/min/1.73 m2 for three months or more, or if it’s above 60 but with signs of kidney damage (e.g., high albumin in urine), it may indicate chronic kidney disease (CKD). Kidney disease is categorized into five stages based on the eGFR value. Stage I refers to an eGFR of 90 mL/min/1.73 m2 or higher, potentially with kidney damage.
Stage II is an eGFR between 60 and 89 mL/min/1.73 m2, with some injury and slight function reduction. In Stage III, the eGFR is between 30 and 59 mL/min/1.73 m2, indicating mild to moderate function loss, where symptoms may appear. Progression to Stage IV means severe impairment, with an eGFR ranging from 15 to 29 mL/min/1.73 m2.
The most advanced stage, Stage V, is characterized by an eGFR below 15 mL/min/1.73 m2, which indicates kidney failure and often requires dialysis or a kidney transplant. For a comprehensive picture, a urine albumin-to-creatinine ratio (uACR) test is often performed alongside eGFR. This test checks for protein or blood in the urine, which can be an early sign of kidney damage even with a normal eGFR.
Next Steps for Kidney Health
If your eGFR results raise concerns or if you are at an increased risk for kidney disease, consulting a healthcare provider is an important next step. They can evaluate your overall health and discuss any further testing or management plans. Risk factors for chronic kidney disease include conditions such as diabetes, high blood pressure, and excess weight.
Further diagnostic tests might include imaging (ultrasound or CT scan) to visualize the kidneys and urinary tract. These scans can reveal issues such as kidney size abnormalities, the presence of kidney stones, or structural problems. In certain situations, a kidney biopsy may be recommended to identify specific types of kidney disease and determine the extent of damage, which helps guide treatment decisions.
Regardless of your eGFR, maintaining kidney health involves several proactive measures. Keeping blood pressure within a healthy range (typically below 120/80) is beneficial. For those with diabetes, careful management of blood sugar levels is also important. Adopting a healthy eating plan, low in salt and saturated fats, also supports kidney well-being.